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Doubt in this trivial awk code

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# 1  
Old 04-14-2011
Doubt in this trivial awk code
Hi,

What is the difference in the following two awk one-liners?
Code:
awk -F, '{s[$2]++} END {if (s[$2] == 1 && $4 > "09:10:00") {print $2, $4}}' f1
awk -F, '{s[$2]++} s[$2] == 1 && $4 > "09:10:00" {print $2, $4}' f1

Even though, all the 2nd column values have duplicate records, the first code does not give any output whereas the second one gives some output. Could anyone please explain the process flow?

This is the data file for which I am working upon:
Code:
01,02877,2011-01-26,08:29:00,IN
01,02877,2011-01-26,17:11:00,OUT
01,05713,2011-01-26,08:11:00,IN
01,05713,2011-01-26,13:47:00,OUT
01,05713,2011-01-26,14:47:00,IN
01,05713,2011-01-26,17:08:00,OUT
01,06771,2011-01-26,09:08:00,IN
01,06771,2011-01-26,18:27:00,OUT
01,15872,2011-01-26,08:08:00,IN
01,15872,2011-01-26,08:57:00,OUT
01,15872,2011-01-26,09:06:00,IN
01,15872,2011-01-26,13:28:00,OUT
01,15872,2011-01-26,13:37:00,IN
01,15872,2011-01-26,15:50:00,OUT
01,15872,2011-01-26,16:01:00,IN
01,15872,2011-01-26,17:18:00,OUT
01,22272,2011-01-26,09:34:00,IN
01,22272,2011-01-26,18:27:00,OUT
01,22671,2011-01-26,08:57:00,IN
01,22671,2011-01-26,16:58:00,OUT
01,29670,2011-01-26,08:27:00,IN
01,29670,2011-01-26,12:08:00,OUT
01,29670,2011-01-26,12:15:00,IN
01,29670,2011-01-26,13:50:00,OUT
01,29670,2011-01-26,14:05:00,IN
01,29670,2011-01-26,16:26:00,OUT
01,29670,2011-01-26,16:32:00,IN
01,29670,2011-01-26,18:38:00,OUT
01,29972,2011-01-26,09:20:00,IN
01,29972,2011-01-26,11:32:00,OUT
01,29972,2011-01-26,12:20:00,IN
01,29972,2011-01-26,13:52:00,OUT

# 2  
Old 04-14-2011
Quote:
Originally Posted by royalibrahim
Hi,

What is the difference in the following two awk one-liners?
Code:
awk -F, '{s[$2]++} END {if (s[$2] == 1 && $4 > "09:10:00") {print $2, $4}}' f1
awk -F, '{s[$2]++} s[$2] == 1 && $4 > "09:10:00" {print $2, $4}' f1

Even though, all the 2nd column values have duplicate records, the first code does not give any output whereas the second one gives some output. Could anyone please explain the process flow?
The 1st will count occurrences of $2 values but only print if $2 has occurred once and the final $4 is larger than "09:10:00".

The 2nd will also count occurrences of $2 values, but will print from each line if $2 has only occurred once so far and the current $4 is larger than "09:10:00".
# 3  
Old 04-14-2011
The first command is totally wrong, after END, only the last record is used for condition compare.

The second one is fine, but can be shorter:

Code:
awk -F, '!a[$2]++ && $4 > "09:10:00" {print $2, $4}'  f1

# 4  
Old 04-15-2011
Quote:
Originally Posted by kato
The 1st will count occurrences of $2 values but only print if $2 has occurred once and the final $4 is larger than "09:10:00".

The 2nd will also count occurrences of $2 values, but will print from each line if $2 has only occurred once so far and the current $4 is larger than "09:10:00".
It looks to me both of your statements meaning the same.

But none of the 2nd field records are free from duplicates. So I feel it should either return all the records or null. But it is not happening

---------- Post updated at 06:06 PM ---------- Previous update was at 06:02 PM ----------

Quote:
Originally Posted by rdcwayx
The first command is totally wrong, after END, only the last record is used for condition compare.
What do you mean by last record? I could not see such restriction in the awk manual.

Also, I have come across many awk codes having records comparing inside END, but not just the last record.
Quote:
Originally Posted by rdcwayx
The second one is fine, but can be shorter:

Code:
awk -F, '!a[$2]++ && $4 > "09:10:00" {print $2, $4}'  f1

Nice, but, could you please explain me what is happening here and how it differs from
Code:
awk -F, '{s[$2]++} END {if (s[$2] == 1 && $4 > "09:10:00") {print $2, $4}}' f1

????
# 5  
Old 04-15-2011
Quote:
Originally Posted by royalibrahim
It looks to me both of your statements meaning the same.

But none of the 2nd field records are free from duplicates. So I feel it should either return all the records or null. But it is not happening
Perhaps a better approach to solving your problem would be to tell us what you want to do with your data file?
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